Speculation has surrounded Costain since Intria suggested that it was looking for a buyer.
However, Intria shares rose sharply last week after reports that the company was confident of quickly overcoming its financial difficulties and therefore planned to retain its stake in the UK contractor.
In a separate development, Costain last week said it had reluctantly accepted an early retirement request from its finance director John Campbell. Campbell, 55, has been with the firm for 30 years. He will be replaced by 35-year-old Miles Roberts at Costain’s annual general meeting on 2 June. Roberts is currently finance director of Three Valleys Water.
Costain’s long-serving head of public relations, Graham Read, is to join Jarvis as director of public relations.